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| From Mules to Motors: The Science and Technology of Gas and Electrical Engines
Emrick Technology Center, Hugh Moore Park, National Canal Museum, Easton, PA
Teacher Program for Teachers in the History Surrounds Us Program, 9 July 2010 |
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Hello! Friday, July 9, 2010 was a special day for teachers enrolled in the History Surrounds Us program. This part of the progam took place at the Emrick Technology Center at Hugh Moore Park, all part of the National Canal Museum in Easton, Pennsylvania. The program began with a keynote address by National Canal Museum Director Dr. Thomas Stoneback, shown on the left. After his presentation, we divided into three groups, with each group cycling through three planned activities: Canal Life, Blacksmith, and From Mules to Motors. This description is mostly appropriate to the Mules to Motors activity, but some of the other adventures we shared that day are also described.
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The teachers are from several New Jersey school districts, including Phillipsburg, Greenwich Township, Lopatcong, Alpha and Bloomsbury. Instructional grade levels ranged from fourth grade through High School. |
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That's Dr. Gary DeLeo (Gary), professor of physics from Lehigh University, on the right. He is heavily involved in science outreach, and ran the program, From Mules to Motors. More about that in a little while. In Canal Life, we learned firsthand what life was like on the canal by harnessing a mule, doing laundry with a washboard and tub, and blowing a conch shell horn. In the Blacksmith activity, shown in the right two photos below, we learned how important blacksmiths were in the daily operation of the canal. We operated a forge and created our own s-hooks using a hammer, anvil and tongs We observed the forging of metal, and even participated. Notice in the close up below on the right how one of us is approaching with a big, heavy hammer (eeekk!!).
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Gary began the From Mules to Motors program with a demonstration showing what happens when a (permanent) bar magnet is moved in and out of a coil of wire, which is in turn connected to a meter that measures electrical current (a "current meter" or "ammeter"). This process is called "electromagnetic induction," whereby a changing magnetic field produces an electric field. The magnetic field in the vicinity of the coil is changing because the magnet is being moved, getting closer to and then farther from the coil. The "induced" electric field pushes electrons through the metal wire (electricity). We noticed that no electricity is produced when the magnet is stationary.
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This is the principle of an electrical generator. In a generator, a coil of wire is rotated in the presence of large, permanent magnets. Since the orientation of the coil is changing with respect to the magnetic field, the magnetic field is increasing and decreasing within the wire as it spins. Gary used a small version of a generator, operated by a hand-crank, to run an electric train, as the children are shown doing below on the left. When Gary connected two crank generators together, we saw something interesting. If we cranked one of them to produce electricity, it made the other one turn, as though it were an electric motor. Which it actually is! In fact, an electrical generator is just an electric motor in reverse, and vice versa. The middle photo shows us with two generators connected together. Check out the video below on the right by clicking the play button on the photo. (And, don't overlook the other videos below!) The video shows two teachers trying to gain control of the other generator by spinning their generator. Although this demonstrated absolutely no scientific principles, it was fun. And teachers are, after all, human beings! |
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| This observation - the reciprocal relationship between generators and motors - raised the question of how an electric motor works. Gary had us connect the ends of a wire wrapped around a nail to a battery. The coil attracted another nail. It became an electromagnet! So, just like a changing magnetic field produces an electric field, changing electricity (the current in the wire) produces a magnetic field. Nature is very symmetrical! |
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Gary prepared a coil of wire for each of us to use in building an electric motor. In addition to the coil of wire, we each got a pair of specially bent paperclips (to support the coil of wire and bring electricity to it), a rubber band to hold the paperclips to the battery, and a magnet. We didn’t know it at the time, but Gary ’s cat helped with the coils of wire! Gary showed us how to put the parts together to make our electric motors
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After listening closely to Gary’s instructions, we put together the parts to make an electric motor that worked! And, we got to keep them and take them home. We were also given a magnetic field viewer that lets us see the magnetic force around a magnet. They are so cool! You can see a video of us using our motors below on the right.
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After playing with our electric motors for a while, we got down to the business of figuring out how they worked. When we examined the coil of wire closely, we noted that the insulation was scrapped off only one side of each of the two wire tabs sticking out of the sides. When the coil was turned so that the bare copper wire was pointing down, electricity was able to flow from the paperclips into the coil. This turned the coil into an electromagnet, which was repelled by the permanent magnet secured to the battery. After the coil rotated 180 degrees, no current could flow through it since the insulation was now down, against the paperclip. Hence, the magnetic force switches off until inertia carries the coil around for another "kick."
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| An electric motor produces motion, but it requires an electric current, which in turn requires motion if we use the process of electromagnetic induction (that is, a generator). So, we need to start with motion. Motion requires force, and forces can be produced by wind, moving water, mules, etc. We decided to examine how fossil fuel energy can be converted to motion. |
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The photos above show us examining little gas engines that used to power model airplanes. Gary got them on eBay. We began by opening them up and examining how they worked. When we turned the propeller shaft, we could see a piston moving up and down. We discovered that the downward force that makes the piston move is produced by the detonation of a mixture of fuel and air, sucked in when the piston is moving down. A crank shaft translates the reciprocating motion of the piston into a rotational motion of the propeller. Although the more efficient four-cycle engine is shown in the figure on the left, the small airplane engines are examples of the simpler two-cycle engines. Before moving on to the next activity, or lunch, we examined the insides of a four-cycle lawn mower engine. |
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We had wonderful learning experiences in all three activities: Canal Life, Blacksmith, and Motors. Afterward, we were provided with a wonderful lunch.
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| Dr. Stoneback brought in purslane, also known as pigweed and pusley. Dating back hundreds of years, it was noted by Pliny the elder... a mucilla- ginous succulent, with vitamins A, B, and C, but implicated in kidney stones. It contains more omega 3 fatty acids than any other leafy vegetable. |
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After lunch, we all went on a Canal Boat ride. The canal boat is pulled by two mules, with one of them shown on the left. The photo on the left below shows Dr. Stoneback talking to one of us before we departed on our ride. We were very excited about the upcoming ride, as you can see by our expressions in the photo below on the right!
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Our guide described the role of the mules, and how these animals were so well suited to their role in pulling the canal boat. We learned that horses would not be well suited for this work, as described by our guide in the video below on the right.
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| Our guide described the nature of the river and the need for a canal in order to successfully navigate the waterway. The guide is shown describing this in the video on the right. |
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The canal boat itself is a wonderful vehicle! The lady shown in the photo on the left steers the boat using the large wooden rudder also shown in the photo. The boat has a lower level, shown in the middle photo below. It is set up with tables, and can be rented for dinners and special occasions. Cool!! The guide is shown describing the boat in the video on the right.
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We turned around when we reached the lock, as shown in the photos below. We also encountered a man who seemed to be concerned that we might steal his chicken!
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Our guide described that the canal boat was originally constructed to move a particular type of coal, called anthracite. He passed pieces of anthracite coal around for all of us to examine. He describes this in the video below on the right.
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| He also demonstrated the use of a conch shell horn. He said he wasn't very good at it, but actually he was! |
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| The ride was so peaceful and relaxing! Gary commented that he would like to ride on the canal boat regularly. He said that many people think it's just for kids. It is a great learning experience for kids (and adults), but adults also need to relax and enjoy life. And, what better place to do it than floating on the canal in a wooden canal boat! Just look at the video of a teacher's foot on the right. Does that foot look relaxed!! |
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When we returned from the canal boat ride, Judy Cannavo described the educational and really fun materials (gifts) that we received. The goody bags contained everything from plans and materials for making aluminum foil boats (to examine buoyancy) to large conch shells! Also, Dr. Stoneback gave us actual mechanical drawing on silk material preserved from Bethlehem Steel!
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Although Gary seems to have avoided appearing in most of the photos, he was all smiles for the full five hours of the program! He had a wonderful experience working with the teachers, and with Tom Stoneback and Judy Cannavo!
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Be sure to visit the National Canal Museum, and the Emrick Technology Center and Canal Boat Ride at Hugh Moore Park in Easton, Pennsylvania.
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Although we have endeavored to exclude photographs where permission has been denied, it is possible for errors to occur. If you would like us to remove a photograph of your son or daughter for any reason, please send me an e-mail message at lgd0@lehigh.edu or call me at 610-758-3413, and we will remove it promptly. Please note that we will never associate a child's full or last name with a photograph except in circumstances where special permission was explicitly provided. Thank you. Gary DeLeo. |
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